code: def test_num_samples_error(self) -> None:
      with self.assertRaises(RuntimeError):
          loss_fn = WMSELoss(num_samples=3)
          x = torch.randn(5, 128)
          loss_fn(x)
  
file_path: lightly/tests/loss/test_WMSELoss.py
imports: import unittest
  import torch
  from lightly.loss.wmse_loss import WMSELoss
label_desc: Use image node_id 5 for calling the testWMSELoss obj's underlying member method code with example usage: obj.test_num_samples_error() without return types